Original list: [T, h, i, s, , i, s, , a, , s, e, n, t, e, n, c, e]
The first occurrence of [i, s] at index: 2
The last occurrence of [i, s] at index: 5
The first occurrence of [] at index: 0
The last occurrence of [] at index: 18
The first occurrence of [uh, oh] at index: -1
The last occurrence of [uh, oh] at index: -1

Note that if we are looking for empty sublist, both indexOfSubList and lastIndexOfSubList found it, but on the first and the last index accordingly.